Mining and Smelting
While the characters are adventurers and not miners there is a natural temptation to take advantage of a resource when it is discovered. The dwarves will be able to use their stone cunning to assess the conditions of any mine tunnels with a simple examination (taking about 10 minutes with a 1/2 Wisdom roll or an hour with a standard wisdom roll) while other characters will need to dig out a sample to test (an hour on a 1/2 wisdom roll and a day on a standard wisdom roll).
Mines have a yield rating in material per man-week of labor (known upon a successful assay of the mine) and a duration rating (number of man-weeks before being played out) which can’t be determined. A man-week is 7 days of labor working 12 hours a day. A typical dwarven mine is big enough for 2 people to work the same shaft, and 2 shifts can be run allowing a maximum of 4 man-weeks of work to be done in 1 week for a given shaft.
It takes 1 day and an INT check to cut down 1 gem to be worthy of being sold (worth 10% the value if not cut), but a failed Int roll cracks the gem (reroll but only half value on a success) while a natural 20 or 2 failed rolls on the same stone destroys it.
It takes 1 day to smelt 100 lb of ore which will yield 1 lb of pure metals (metals are not lost to a poor roll, but another day of work is needed). Smelted metals can be put into molds the same day they are smelted if available.
Molds can be made of clay in 1 day using a forge as a kiln and are usually made for 1 lb bars or 1/50 lb coins (charisma check to make artistic or forged stamps on bars/coins).
Gems and metals refined by characters sell at the same rate as items found, full value in Raven’s Bluff and 10% below listed value in most adventuring towns.
If there is no established mine a character can prospect an area for ore deposits. This takes a week of survey work for a 1/2 Wisdom check. If successful the DM can roll for a deposit. Each check in the same 10 mile hex takes a -2 to the roll, there may be multiple deposits or deposits may have been missed, but the chances are less (the -2 penalty applies to any character checking the hex, not just the same one, as a result finding a new mine near a settlement is extremely unlikely). A new mine will yield 1d100 man-weeks of product before playing out.
Prospect D% (Yield in finished product, ore weighs 100 times as much)
1-30: Copper (1d10x100 pounds per man-week)
31-40: Tin (1d10x150 pounds per man-week)
41-66: Lead (1d10x200 pounds per man-week)
67-84: Iron (1d10x200 pounds per man-week)
85-92: Silver (1d10x25 pounds per man-week)
93-97: Gold (1d10x10 pounds per man-week)
98: Platnum (1d10x5 pounds per man-week)
99: Gems (roll below)
00: Special (Mithril or Adamantine 1d10 pounds per week, or roll twice above)
01-25 Ornamental Stones (10 GP, 4d6 per man-week)
26-50 Semi-Precious Stones (50 GP, 3d6 per man-week)
51-70 Fancy Stones (100 GP, 2d6 per man-week)
71-90 Precious Stones (500 GP, 1d6 per man-week)
91-99 Gem Stones (1,000 GP, 1d3 per man-week)
00 Jewel Stones (5,000 GP, 1d2 per man-week)